1. Field of the Invention
This invention relates generally to supplying electrical power to electronic and other electrical devices; and more particularly to systems and apparatus for providing electrical power to operate any of a multiplicity of such devices.
2. Prior Art
In many situations it is desirable to make general provision for supplying electrical power to a device that will be provided later, as for instance by a customer or other user of a multiuser facility. By "multiuser facility" I mean to encompass a facility used by just a small number of people at a time, or even one person at a time--but in which the people or person using the facility at any time are typically different from the people or person using it at other times--and in any event the individual device cannot be specified or identified in advance.
Mobile facilities, which is to say vehicles--such as ships, airplanes, trains, buses and automobiles are examples of such multiuser facilities. Continuing in the same vein, stationary facilities of interest for present purposes include transportation terminals such as airport lounges.
Other pertinent types of multiuser facilities include hotels, restaurants, convention and exhibit halls, schools, laboratories and offices. Problems related to supply of electrical power in all such multiuser facilities will now be discussed.
As will shortly appear, however, it is possible to analyze and generalize the problems under discussion. Such generalization will lead to realization that related problems, such as economic inefficiencies, are present even in single-user circumstances.
In a mobile facility and elsewhere far from the user's own home or office it can be particularly important to supply electrical power exclusively in correct form for the device which will use that power, and furthermore exclusively to devices which are suitable for operation in the particular facility. For instance, supplying power in an incorrect form (for instance incorrect voltage) may damage the device to which the power is supplied, and such damage may be especially problematic for a user who is in transit--when repair or replacement may be unfeasible.
In a mobile facility, supplying power in an incorrect form may also cause problems more intimately related to the power-supplying equipment--by damaging that equipment, or taking it temporarily out of service. Such equipment may be particularly limited in current-carrying capacity or in ability to accept loads or signals reflected from the electrical device back into the supply.
Here too, repair or replacement of a mobile power supply en route may be unfeasible on account of the limitations inherent in travel. Similarly some candidate solutions such as fuses and circuit breakers within vehicles pose their own inherent undesirable costs and inconveniences.
Even more importantly, some electrical and particularly electronic devices interfere with safe operation of nearby equipment such as a vehicle in which such devices are used. A classical and well-known example of this problem is computer-generated interference with air navigation.
Thus for some situations it may be desirable to entirely deny, rather than supply, power for particular individual devices. To put it another way, it may be desirable to entirely deny power for any device that is not approved for use.
To facilitate generality of expression in this document, however, denying power will be encompassed within the concept of selecting power parameters for the particular combination of electrical device and facility--and then applying power "according to the power parameters". In other words, for purposes of this document it is to be understood that selected parameters in some cases may be "no voltage and no current".
Two modern developments make the problems outlined above particularly important. First is a proliferation of portable electronic devices which are nominally internal-battery operated, but which can operate from external power, and whose batteries require replacement or recharging at intervals considerably shorter than the uninterrupted duration of modern travel (as for transcontinental air flights)--and whose direct-external-power and charger-external-power requirements are extremely variegated.
Even for short-range travel, use of external power when available is usually preferable to conserve batteries for environments lacking external power. Such portable electrical devices range from ordinary audio cassette players and hand-held electronic games, through portable television sets and video cameras, to full-capability personal computers, FAX machines and even computer printers.
Nominal power requirements of all these devices are extremely diverse as to current drain, voltage, direct vs. alternating waveform, and in the latter case frequency. Furthermore whereas some devices tolerate large departures from nominal values, others accommodate only rather tight tolerances in power characteristics.
Accompanying a great many of these devices, moreover, are rechargers for the internal batteries. In most cases the input-power specifications for the chargers are entirely different from the direct-use external power specifications.
A second pertinent modern development is that some airplane-manufacturer interest has arisen in providing at each passenger seat, or for instance at each business or first-class passenger seat, an equipment pod that includes certain special amenities. Such amenities may for example include a separately deployable video monitor, and in particular a courtesy electrical-connector receptacle for supplying electrical power to laptop computers, dictating machines and the like.
Analogously in vehicles (such as ordinary buses) where navigational interference is not a problem, power receptacles for cellular telephones will be appropriate. More generally it may be desirable, in aircraft as well as other facilities, to power through such receptacles any of the great range of portable electronics mentioned above.
In order to make use of such a power-supply receptacle, each electronic device (computer, telephone, tape recorder etc.) must have a cable terminated compatibly with the receptacle. Such a compatible termination or adaptor is readily provided, but--by giving all devices in common an equal access to the facility power supply--only makes more severe the more-fundamental device-compatibility problems discussed earlier.
As will be understood, provision of such amenities at each seat in each aircraft in an entire new aircraft-model line aggravates in a time-immediate way the problems discussed above. This particularly focused need, however, is magnified by the general desirability of solving these problems for other types of vehicles and facilities.
Once attention is directed to the special problems of providing power in multiuser facilities, it can be appreciated that the broad diversity of electronic-device power requirements has itself created a very uneconomic variegation in commercially available separate power-supply modules. This diversity of power-supply units in turn has been fed by various factors, probably including for small-portable-device manufacturers the desirability of
(a) supplying a single model for use in various countries with divergent house-voltage specifications, and PA1 (b) avoiding submission of their products to the expensive and demanding sort of safety tests generally required for house-voltage apparatus. PA1 at least one conductor that serves as part of the power-passing means but not the information-accepting means; and PA1 at least one other conductor that serves as part of the information-accepting means but not the power-passing means.
A large number of different power-supply modules on the market introduces a significant element of added costs. Such costs are embedded throughout manufacturing, warehousing, inventorying, shipping, and related paperwork for all the related products.
Some manufacturers have attempted to reduce the maze of power-supply modules which travelers need, by providing custom battery-charger/power-supply input units that operate on any voltage from about 100 through 250 Vac, and at 50 or 60 HZ. Some such units may automatically test the voltage and frequency available, and modify their own power-input characteristics accordingly.
Devices which are so equipped accordingly require only a socket adapter when transported abroad, and thus solve a major problem of diversity as between countries. As will be understood, however, this type of enhancement does nothing to reduce the uneconomic diversity of power-supply specifications or modules within any country, as between different electronic devices.
In a hitherto unrelated field, it is known to provide and employ an integrated-circuit memory unit, such as a ROM, RAM, PROM or EPROM chip, for identification purposes. Modern semiconductor technology makes possible the provision of electronic "keys" or identification units that can each carry one of an essentially unlimited number of electronic key codes.
If desired, each code can be made unique, or substantially so. On the other hand, if preferred a large number of chips can be made with the same code--for use in distinguishing associated people or items from one another by categories.
For example, the DS 2400, 2401 and 2502 circuit devices manufactured by Dallas Semiconductors, Inc., of Dallas, Tex., each have a numerical capacity equal to the fourteenth power of ten, or one hundred trillion, and can be manufactured in such a way that no two of them hold the same number. Thus the numerical range of ROMs and PROMs now on the market exceeds the earth's population by several orders of magnitude.
The above-mentioned Dallas Semiconductors devices are called by the firm its "Touch Memory" chips, as the devices are able to read or write with momentary contact. The firm houses each chip in a stainless steel container which the firm calls a "MicroCan". This coin-shaped container is 16.3 mm in diameter and 3.2/5.8 mm in height.
It is mounted it with one flat circular face of the can secured to the flat surface of a generally rectangular thin flat ID card or a thin flat generally oblong-shaped key fob. A user holds and manipulates the card or fob so as to insert the "MicroCan" into--for example--a generally forwardly facing electronic-lock receptacle, through which data in the chip are read into electronic circuitry within the lock.
The Dallas chips, housed as just described, are advertised for use in identifying a great variety of different things and entities such as people, livestock, or warehoused merchandise; for instance it is now advertised as useful for identifying different kinds of batteries in an inventory. As mentioned earlier, it has not been suggested heretofore that such ROM, PROM etc. chips might have any application to solving the multiple-power-supply problems discussed previously.
As can now be seen, the prior art has failed to provide solutions to important problems in the portable-electronics field.